Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Biosurfactants are one of the mainly class of natural surfactants and are classified according to their chemical composition and microbial origin. The production of biosurfactants by microorganisms is intimately linked to the environmental and nutritional conditions provided and the factors that influence microbial growth also affect their production. Currently, most of the compounds are synthetic surfactants and the main factor restricting the widespread use of biosurfactants is their production cost when compared to the ones with synthetic origin. The solid-state and submerged fermentation can be used for the production of biosurfactants, but the solid-state fermentation is considered a simple technology for production of compounds with interest and an alternative to avoid foaming, a limiting factor in obtaining these compounds by submerged fermentation. This study aimed to evaluate the influence from the pre-inoculum use in biosurfactant production by Bacillus subtilis in solid state fermentation. The fermentation was carried out in polyethylene bags containing 10 g of wheat bran and phosphate buffer solution and glycerol concentration to obtain 60% moisture and incubated in a chamber at 37°C for 96 hours. The fermentation was conducted in three ways: without pre-inoculum...

Tese de Doutoramento em Engenharia Química e Biológica; This thesis is focused on physiological aspects of the yeasts used in two alcoholic
fermentation processes: primary brewing fermentation and fermentation of lactose
(particularly lactose derived from cheese whey) to ethanol by recombinant Saccharomyces
cerevisiae flocculent strains.
The brewing fermentation is probably the most extensively studied alcoholic fermentation
process. Nevertheless, developments in brewing technology demand deeper understanding
of yeast physiology under process conditions. The studies with brewer’s yeast reported in this
thesis addressed two specific questions that had not yet been effectively investigated. First, it
is here directly demonstrated for the first time that the brewer’s yeast lipid composition,
particularly the amounts of sterols and unsaturated fatty acids, affects the activity of maltose
transporters. The maltose uptake rates were correlated with the amount of ergosterol in yeast,
showing that proper function of the maltose permeases requires adequate amounts of
ergosterol in the plasma membrane. This effect may partly explain the low maltose (and
maltotriose) transport rates at the beginning and during the second half of brewery
fermentations...

We used a cultivation-independent, clone library-based 16S rRNA gene sequence analysis to identify bacterial communities present during traditional fermentation in sour cassava starch, cachaça and cheese production in Brazil. Partial 16S rRNA gene clone sequences from sour cassava starch samples collected on day five of the fermentation process indicated that Leuconostoc citreum was the most prevalent species, representing 47.6% of the clones. After 27 days of fermentation, clones (GenBank accession numbers GQ999786 and GQ999788) related to unculturable bacteria were the most prevalent, representing 43.8% of the clones from the bacterial community analyzed. The clone represented by the sequence GQ999786 was the most prevalent at the end of the fermentation period. The majority of clones obtained from cachaça samples during the fermentation of sugar cane juice were from the genus Lactobacillus. Lactobacillus nagelli was the most prevalent at the beginning of the fermentation process, representing 76.9% of the clones analyzed. After 21 days, Lactobacillus harbinensis was the most prevalent species, representing 75% of the total clones. At the end of the fermentation period, Lactobacillus buchneri was the most prevalent species, representing 57.9% of the total clones. In the Minas cheese samples...

ABSTRACT: The potential of ligninases as a green tool for effective valorization of lignin can be shown through enzymatic cocktails containing different lignin degrading enzymes. The present study deals with the screening of potential fungal strains useful for the liquefaction of bark containing lignin. Three different local isolates (Pleurotus ostreatus POS97/14, Pycnoporus sanguineus and the local isolated fungal strain) were selected out of ten different strains for ligninases production. Maximum production of enzymes was observed in the local isolated fungal strain after ten days in submerged fermentation. The isolated fungal strain produces ligninases mainly for manganese peroxidase (MnP). The enzyme oxidized a variety of the usual MnP substrates, including lignin related phenols. Furthermore, the partial purification for MnP was determined by FPLC and the molecular weight was evaluated by SDS-PAGE.; 2012

Among the main challenges in the beer industrial production is the market supply at the lowest cost and high quality, in order to ensure the expectations of customers and. consumers The beer fermentation stage represents approximately 70% of the whole time necessary to its production, having a obligatoriness of strict process controls to avoid becoming bottleneck in beer production. This stage is responsible for the formation of a series of subproducts, which are responsible for the composition of aroma/bouquet existing in beer and some of these subproducts, if produced in larger quantities, they will confer unpleasant taste and odor to the final product. Among the subproducts formed during the fermentation stage, total vicinal diketones is the main component, since it is limiting for product transfusion to the subsequent steps, besides having a low perception threshold by the consumer and giving undesirable taste and odor. Due to the instability of main raw materials quality and also process controls during fermentation, the development of alternative forms of beer production without impacting on total fermentation time and final product quality is a great challenge to breweries. In this work, a prior acidification of the pasty yeast was carried out...

The adapted metabolic response of commercial wine yeast under prolonged
exposure to concentrated solutes present in Icewine juice is not fully understood.
Presently, there is no information regarding the transcriptomic changes in gene
expression associated with the adaptive stress response ofwine yeast during Icewine
fermentation compared to table wine fermentation. To understand how and why wine
yeast respond differently at the genomic level and ultimately at the metabolic level during
Icewine fermentation, the focus ofthis project was to identify and compare these
differences in the wine yeast Saccharomyces cerevisiae KI-Vll16 using cDNA
microarray technology during the first five days of fermentation. Significant differences
in yeast gene expression patterns between fermentation conditions were correlated to
differences in nutrient utilization and metabolite production. Sugar consumption, nitrogen
usage and metabolite levels were measured using enzyme assays and HPLC. Also, a
small subset of differentially expressed genes was verified using Northern analysis. The
high osmotic stress experienced by wine yeast throughout Icewine fermentation elicited
changes in cell growth and metabolism correlating to several fermentation difficulties...

The yeast Saccharomyces cerevisiae has a fundamental role in fermenting grape juice to wine. During alcoholic fermentation its catabolic activity converts sugars (which in grape juice are a near equal ratio of glucose and fructose) and other grape compounds into ethanol, carbon dioxide and sensorily important metabolites. However, S. cerevisiae typically utilises glucose and fructose with different efficiency: glucose is preferred and is consumed at a higher rate than fructose. This results in an increasing difference between the concentrations of glucose and fructose during fermentation. In this study 20 commercially available strains were investigated to determine their relative abilities to utilise glucose and fructose. Parameters measured included fermentation duration and the kinetics of utilisation of fructose when supplied as sole carbon source or in an equimolar mix with glucose. The data were then analysed using mathematical calculations in an effort to identify fermentation attributes which were indicative of overall fructose utilisation and fermentation performance. Fermentation durations ranged from 74.6 to over 150 h, with clear differences in the degree to which glucose utilisation was preferential. Given this variability we sought to gain a more holistic indication of strain performance that was independent of fermentation rate and therefore utilized the area under the curve (AUC) of fermentation of individual or combined sugars. In this way it was possible to rank the 20 strains for their ability to consume fructose relative to glucose. Moreover...

Optimizing ethanol yield during fermentation is important for efficient production of fuel alcohol, as well as wine and other alcoholic beverages. However, increasing ethanol concentrations during fermentation can create problems that result in arrested or sluggish sugar-to-ethanol conversion. The fundamental cellular basis for these problem fermentations, however, is not well understood. Small-scale fermentations were performed in a synthetic grape must using 22 industrial Saccharomyces cerevisiae strains (primarily wine strains) with various degrees of ethanol tolerance to assess the correlation between lipid composition and fermentation kinetic parameters. Lipids were extracted at several fermentation time points representing different growth phases of the yeast to quantitatively analyze phospholipids and ergosterol utilizing atmospheric pressure ionization-mass spectrometry methods. Lipid profiling of individual fermentations indicated that yeast lipid class profiles do not shift dramatically in composition over the course of fermentation. Multivariate statistical analysis of the data was performed using partial least-squares linear regression modeling to correlate lipid composition data with fermentation kinetic data. The results indicate a strong correlation (R² = 0.91) between the overall lipid composition and the final ethanol concentration (wt/wt)...

Yeast (Saccharomyces cerevisiae) plays a key role in the completion of several fermentations including those used for beverage and bioethanol production. In the wine industry, slow or incomplete alcoholic fermentation is still a challenging problem and often results in increased costs of production and decreased wine quality. One of the reasons for the persistence of this problem could be the trend towards rising sugar concentrations in grape musts. What is already a high sugar concentration fermentation (~200 g L⁻¹ or more) has increased by some 20 – 40 g L⁻¹ due to climate warming and winemaker pursuit of ripeness. In this project we aim to gain a better understanding of how wine yeast cope in high sugar fermentations (HSF) to help develop strategies for managing these types of grape musts. With the availability of collections of laboratory yeast including gene deletion and overexpression libraries and the development of techniques used for whole genome analysis, it is now possible to investigate yeast biology under oenological conditions with a systems biology approach. A number of genome-wide studies of yeast have previously been conducted to identify yeast genes involved in sensitivity to individual stresses present during fermentation. However...

BACKGROUND: Wine fermentation is a harsh ecological niche to which wine yeast are well adapted. The initial high osmotic pressure and acidity of grape juice is followed by nutrient depletion and increasing concentrations of ethanol as the fermentation progresses. Yeast's adaptation to these and many other environmental stresses, enables successful completion of high-sugar fermentations. Earlier transcriptomic and growth studies have tentatively identified genes important for high-sugar fermentation. Whilst useful, such studies did not consider extended growth (>5 days) in a temporally dynamic multi-stressor environment such as that found in many industrial fermentation processes. Here, we identify genes whose deletion has minimal or no effect on growth, but results in failure to achieve timely completion of the fermentation of a chemically defined grape juice with 200 g L-1 total sugar. RESULTS: Micro- and laboratory-scale experimental fermentations were conducted to identify 72 clones from ~5,100 homozygous diploid single-gene yeast deletants, which exhibited protracted fermentation in a high-sugar medium. Another 21 clones (related by gene function, but initially eliminated from the screen because of possible growth defects) were also included. Clustering and numerical enrichment of genes annotated to specific Gene Ontology (GO) terms highlighted the vacuole's role in ion homeostasis and pH regulation...

Due to the artisan nature of the production process of tepache, there is no uniformity in fermentation conditions and raw material used. The fermentation is crucial to the final characteristics of tepache and there is a certain degree of ignorance of related organisms and the level of acceptance among consumers. In this study, tepache fermentation conditions (concentration of sugars, initial pH, temperature and fermentation time) were evaluated to enable correlating the formation of products of fermentation (lactic, acetic and ethanol) with the degree of acceptance of the beverage among consumers. Sensory evaluation was measured on a 9-point hedonic scale. Results were analyzed using the response surface methodology (RSM) which showed that the fermentation conditions for higher acceptanco were 22ºC, 10% (mass/volume) of sugars (brown sugar), 72 h of fermentation and an initial pH of 5. According to this study, to have a wider acceptance the beverage must contain about 7 g/L of ethanol, no more than 5 g/L of lactic and acetic acid, and 70 g of sucrose/L. Likewise, yeasts present in the fermentation were identified and it was found that Saccharomyces cerevisiae is the predominant species.

The current study evaluated the diversity of yeast species in Cabernet Sauvignon grape must derived from three neighbouring vineyards from a similar terroir but on which significantly different management practices are employed. The fermentation kinetics and yeast population dynamics were monitored from the beginning to the end of spontaneous fermentation. The grape musts were characterised by distinct yeast populations comprising oxidative, weakly fermentative and strongly fermentative yeasts. Different combinations of dominant non-Saccharomyces yeasts were observed in each must, with significantly different assortments of dominant species, including Starmerella bacillaris (synonym Candida zemplinina), Lachancea thermotolerans, Hanseniaspora uvarum, Candida parapsilosis and Wickerhamomyces anomalus. None of these yeast consortia appeared to affect the growth of Saccharomyces cerevisiae or inhibit the overall progress of fermentation. However, the percentage of fermentative yeasts was positively correlated with the fermentation rate. Glucose and fructose consumption rates suggested active participation of both glucophilic and fructophilic yeasts from the onset of fermentation. The data highlight two parameters, viz. initial cell concentration and yeast community composition...